package com.springcloud.order.lb.lbImpl;

import com.springcloud.order.lb.LoadBalancer;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Component
public class MyLb implements LoadBalancer {


    private AtomicInteger nextServerCyclicCounter;

    public MyLb() {
        nextServerCyclicCounter = new AtomicInteger(0);
    }

    public final int getAndIncrement() {
        int current;
        int next;
        do {
            current = this.nextServerCyclicCounter.get();
            next = current >= 2147483647 ? 0 : current + 1;
        } while (!this.nextServerCyclicCounter.compareAndSet(current, next));
        System.out.println("next = " + next);
        return next;
    }

    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
